allele: One of several possible values that may exist for a genetic marker. Here it means the specific number of repeats at a given location on the Y-chromosome.
base: one of four molecules that, in combination with a phosphate, are the building blocks of DNA. They are adenine (A), cytosine (C), guanine (G), and thymine (T) and, when paired with their complements (A with T and C with G), form the ladder rungs of the DNA molecule.
chromosome: a long strand of DNA which contain the hereditary information. The human cell contains 23 pairs of chromosomes, receiving one chromosome of each pair from the father and one from the mother.
DNA: DeoxyriboNucleic Acid - The double stranded molecule that encodes genetic information. It is made-up of phosphate, deoxyribose and four bases; adenine (A), cytosine (C), guanine (G), and thymine (T).
haplotype: A group of individuals whose DNA contains a specific mutation, which is the group's defining marker. This mutation links the members of the group back to the markers first appearance in the group's most recent common ancestor (MRCA). Everyone whose DNA contains this markers is descended from this one individual.
haplotype: The complete set of marker values representing the test results reported for a specific individual.
marker: A specific location on the Y-chromosome with known characteristics, which is used for comparison purposes.
mitochondria: an ancient parasitic bacteria that produces energy in each cell. It has its own DNA which is passed, via the human egg, from mother to child without recombining, and therefore is very stable, which makes it ideal for tracing genetic histories.
modal: The most common, and therefore usually the oldest, haplotype which represents a set of marker values that defines a specific genetic line, along with its later descendant variations.
MRCA: Most Recent Common Ancestor - The most recent ancestor common to two individuals, such as a shared grandparent or great-grandparent, from which the two individual's separate lines diverged.
nucleotide: a combination of one of the four DNA bases (i.e., adenine, cytosine, guanine, and thymine) plus a phosphate. Nucleotides are the building blocks of the DNA molecule.
STR: Short Tandem Repeats - a short sequence of DNA, repeated a number of times in continuous succession.
Y-chromosome: One of the two so-called sex chromosomes, which determines the gender of a human fetus. Females have two X-chromosomes, while males have an X and a Y. Only males have a Y-chromosome and if an egg is fertilized which a sperm containing a Y-chromosome, it too will be male. If not, it will be female. Since the Y-chromosome is thus passed from father to son, it is ideal for tracing male genetic histories.
Version: 102; Created on December 5, 2007 at 12:30 pm